First week of February was deadliest in state for flu season

Public health officials on Friday reported that there were 36 flu-related deaths in California during the first week of February, making that the deadliest week in what was already a brutal influenza season.

But infectious disease experts and doctors working on the front lines said there are signs that the season may finally be winding down, with slightly fewer hospitalizations and visits to emergency rooms and health clinics in recent weeks.

This influenza season has been the worst since at least the historic 2009 season, when the swine flu was pandemic and people all over the country were lining up for vaccines and access to care.

Experts cautioned that even though it seems likely the worst is over, it’s still too soon to absolutely determine whether the current season has peaked. But peak or not, California is probably facing another six weeks or so of heightened flu activity.

“Happily, the numbers seem to be diminishing,” said Dr. Jeffrey Silvers, medical director of infectious disease at Sutter Health. “But we’re going to have influenza for a while. People should still get their vaccine if they haven’t already.”

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This season’s deadly flu epidemic has led to widespread crowding of hospitals and doctors’ offices across the state. In the Bay Area, many hospitals called in extra staff to cover the deluge of sick patients, or canceled elective surgeries to free up resources. In some parts of the state, hospitals set up triage tents outside emergency rooms just for patients with flu symptoms.

So far this season, California has reported 163 flu deaths among people under age 65, according to the update released Friday by the state Department of Public Health. The state does not report deaths in people age 65 and older, in part because fatalities among older people are so common that reporting them all would overwhelm surveillance systems.

The U.S. Centers for Disease Control and Prevention only reports pediatric deaths from the flu. This season, 63 children age 18 and under throughout the nation have died, according to the CDC.

The total number of flu deaths among people under 65 in California varies widely from season to season, but it typically hovers around 100. That makes this year’s count particularly high, especially since the flu season — which runs from about October to May — won’t officially end for another four months.

According to the public health department, the bulk of the state’s flu deaths— 91 total — happened in Southern California. Thirty deaths have been reported in the Bay Area.

Several factors have made this season especially rough, but the main issue is that the dominant flu strain is an aggressive one. The type A, subtype H3N2 strain tends to strike older people and young children, who are already more vulnerable to flu. Symptoms from H3N2 often are more intense than with other strains, and people are more likely to suffer additional complications, such as pneumonia, and be hospitalized.

Plus, the flu vaccine is not especially strong against H3N2. Reports have shown it may be able to prevent only about 1 in 10 flu cases.

Lately, positive tests for less deadly B flu strains have started to pick up. As of the first week of February, there were almost as many positives for B strains as for A strains in California, according to Friday’s public health report.

That’s a somewhat good sign, since it likely means that the more virulent A strain is dropping off. But it could mean that the state is facing another — albeit likely smaller and less severe — uptick in flu reports, infectious disease experts said.

“Flu B is holding steady, and if anything increasing a little bit,” said Dr. Randy Bergen, clinical lead for Kaiser Permanente’s flu vaccination program in Northern California. “We’re seeing flu B especially in the school-age children. That does give me a bit of a pause — the epidemics always start in the schools and then spread.”

Another factor could prolong this year’s flu season: the Olympics. People participating in or observing the Games could be exposed to flu strains in South Korea that haven’t been widely circulating in the United States this year, experts said. That could set off a brand new surge here after the Games end.

“We’ll be looking at what people come back from the Olympics with,” Silvers said.